Method for making filter cigarettes using light energy to make perforations in the filter tipping wrap

ABSTRACT

Perforations are made at locations spaced about the periphery of a cigarette by conducting separate parts of a laser beam through respective separate light paths which intersect such spaced peripheral locations.

FIELD OF THE INVENTION

This invention relates to methods and apparatus for perforation of thesurface of articles and pertains more particularly to the manufacture ofcigarettes having dilution characteristics attained by perforation offilter tipping paper using laser apparatus.

BACKGROUND OF THE INVENTION

Practices examined heretofore in the cigarette industry for perforationhave included mechanical puncture, electrical arc striking and laserbeam treatment. These practices typically have involved perforating aweb of filter tipping paper with smoke dilution thereby being effectedin the cigarette filter, upon wrapping the perforated tipping paper onfilter plugs.

For operation on the assembled filter cigarette, i.e., whereperforations are to be made in the tipping paper after wrapping thereofupon the plug and following joinder of the tobacco cylinder and plug,the laser approach is more expeditious than the other foregoingpractices. One known system for this purpose continuously rotates anotherwise complete cigarette in relation to a pulsed point-focused laserbeam. On each pulse, a single hole is made in the cigarette filter.After completion of rotation, the cigarette bears a plurality ofcircumferentially spaced holes at a common location axially of thecylindrical plug. Since cigarettes are made back-to-back in such knownsystem and then mutually severed midway of the dual filter plug, thelaser beam is split into two beams which are incident on mutually spacedaxial locations on the dual plug.

Such known laser approach has advantage in not requiring perforation oftipping paper as a practice preparatory to cigarette making and furtherin providing possible selection of dilution characteristics optionallyat the cigarette maker on otherwise complete cigarettes by adjustment oflaser apparatus operation, as contrasted with need for preselection ofproperly perforated tipping paper for each diverse-dilution cigarette.On the other hand, such known laser-perforation system requires thateach cigarette to be perforated be subjected to a full revolution aboutits longitudinal axis while such axis is in spatially fixed disposition.In the known system, this relatively complex task is practiced bycapturing each cigarette separately between first and second drums in arecess extending about the first drum surface and rotating the drums atidentical lineal surface speed.

In effect, this known system functions, for each perforation made, inrelated manner to the several laser sheet material perforating systemsshown in the reference discussed in the prior art statement filed hereinpursuant to 37 CFR 1.97 and 1.98.

CROSS-REFERENCE TO RELATED APPLICATIONS

The invention, as described below, is claimed in its several differentaspects in this application and two other commonly assigned applicationsfiled on even date herewith and respectively entitled "Apparatus forPerforating Articles by Laser", Ser. No. 908,522 and "Apparatus forLaser Perforation of Transported Articles", Ser. No. 908,523.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide improved methods andapparatus for laser perforation of articles of manufacture.

A more particular object of the invention is to enable expeditious laserperforation of the periphery of otherwise complete filter cigarettes.

In attaining the foregoing and other objects, the invention providespractice wherein a plurality of circumferentially spaced holes are madesimultaneously, by laser treatment of a cigarette, while the cigaretteis in essentially single angular disposition with respect to itslongitudinal axis. The invention provides apparatus having componentsfor conducting light energy simultaneously to spaced circumferentiallocations on a cigarette in the course of transport thereof through acigarette assembly unit. Apparatus in accordance with the inventionpreferably includes a pulsed laser and optical structure receiving thelaser output pulse and simultaneously conducting separate parts thereofin different light paths which intersect diverse locations spaced aboutthe periphery of a cigarette. The system for transporting cigarettesincludes a rotative drum which supports cigarettes for perforation andprovides for synchronism between drum rotation and laser pulsing. Bysuch practice and apparatus, the cigarette maker may operate withbenefit of the invention without change in the production efficiencyattained in conventional operation thereof, requiring at most theaddition to the assembly unit of exit structure transferring cigaretteswith filter portions thereof circumferentially exposed for laserperforation.

The foregoing and other objects and features of the invention will befurther understood from the following detailed description of preferredpractices and embodiments thereof and from the drawings wherein likereference numerals identify like parts throughout.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation illustrating transport apparatus for filtercigarettes.

FIG. 2 is a sectional view as seen from plane II--II of FIG. 1 andincluding a showing of additional components of the system of theinvention.

FIG. 3 is an elevational view of the perforating optics of FIG. 2 asseen from plane III--III of FIG. 2.

FIG. 4 is a sectional view as seen along line IV--IV of FIG. 3.

FIG. 5 is a front elevational view of the hub reflector unit of FIG. 4.

FIG. 6 is a side elevational view of the FIG. 5 unit.

FIG. 7 is a sectional view as seen along line VII--VII of FIG. 5.

FIG. 8 is a front elevational view of a spherical reflector of the FIG.3 perforating optics.

FIG. 9 is a sectional view as seen along line IX--IX of FIG. 8.

DESCRIPTION OF PREFERRED PRACTICES AND EMBODIMENTS

Referring to FIGS. 1 and 2, main frame 10 of a cigarette maker supportsejection drum 12, perforation support drum 14 and transfer drum 16. Thepath P of cigarettes issued by the maker and traversing the drums isindicated by the broken arrow line, perforated cigarettes beingtransferred from drum 16 to an output belt conveyor (not shown).

Drum 14 has spaced peripheral grooves 18 running axially thereof,cigarettes C shown in phantom in FIG. 2, being supported in the grooveswith the filter tip portion extending outwardly of drum face 14a. Ducts20 extend, in sets of three as shown, from the floor of grooves 18through drum 14 and in registry with counterpart fluid passages 22,peripherally continuous over drum portion 14b and extending to theinterior of vacuum shoe 24. Shoe 24 is secured to manifold 26 and is influid communication therewith. By negative pressurization of manifold26, suction capture of cigarettes C is effected in travel thereof overpath P in FIG. 1.

Housing 28 supports shoe 24 and manifold 26 and seats bearings 30 and32. Shaft 34 is thus supported for rotation of drum 14 by driving ofgear 36. Hub 38 and timing disc 40 are rotative with drum 14, disc 40having a crenelated periphery, individual radial lugs thereofcorresponding in number with the number of grooves 18. Each lugactivates Hall-effect switch 42 on passage through the field ofsensitivity of the switch, providing an electrical pulse output on line44. Such pulses are coupled to laser 46 for short duration energizationthereof. Hub 38 includes sectoral slots for receipt of screws 48,whereby timing disc 40 may be rotated into desired position forsynchronizing operation of the laser with shaft 34 angular position.

Upwardly of drum 14, main frame 10 has secured thereto mounting 50. Themounting in turn supports perforation optics assembly 52, the structuraldetail of which is discussed below. On each pulsing, laser 46 issues itsoutput beam 54 to assembly 52 which processes the beam to issueperforating beams 56 onto the periphery of the cigarette disposed inposition shown in FIG. 1. Perforation of the cigarette filter is thusachieved simultaneously as to all perforations while the cigarette is inessentially single angular disposition with respect to its longitudinalaxis. Since drum 14 preferably rotates continuously during operation ofthe system, the cigarette is transported in path P during perforation bysome actual measure, despite that it is maintained by vacuum in fixedposition in the drum groove. Shortening of the duration of the laserpulse will, however, effectively "stop" the cigarette, i.e., there is nopractical measure of transport during perforation. On the other hand,the invention contemplates variation of dilution characteristics bypermitting a practical measure of transport during perforation, bylengthening perforations as the cigarette is moved in path P duringlaser pulsing. An alternative dilution control measure is to modify beamenergy.

In practice of the invention, laser 46 is preferably a TEA (transverseexcited atmospheric) CO₂ Laser, such as a Series TE-801A Line TunableMultigas Laser, produced commercially by Lumonics Research Limited,Ontario, Canada. Such laser provides a large diameter beam of highintensity and short duration and is readily pulsed at ratescorresponding to rotational transport speeds of drum 14.

In adapting laser apparatus to the perforation of cigarettes in mannernot requiring rotation of individual cigarettes about their axesthroughout perforation thereof, and permitting operational speedconsistent with customary cigarette making speeds, applicants preferablyemploy perforation optics 52 as shown in FIGS. 3 and 4. Principaloptical components of the perforation optics are reflective elements 58and 60 which are supported successively between the laser light-issuinglocation and the cigarette perforating location. Such elements areoperative in conjunction to separate received light energy into discreteparts and to focus each such discrete part for incidence thereof on adistinct one of a plurality of locations about the periphery of thecigarette.

In FIGS. 3 and 4, the perforation optics housing is comprised of supportring 62, back plate 64, front plate 66 and manifold 68. Support ring 62includes keyway 62a and bores 62b for securement to parent supportstructure (mounting 50) and has further bores therethrough for receiptof interiorly threaded bolts 70, counterpart flat head fasteners 71 anddowels 72, 73 with attendant securement of the back plate, front plateand manifold to the support ring.

Manifold 68 and front plate 66 both have central openings registeringwith one another to define housing light admission port 74. Back plate64 has secured centrally thereto, by flat head fasteners 76 and dowel78, hub reflector unit 80. Unit 80 is centered about optical axis 82 ofadmission port 74 and provides an angular succession about axis 82 ofplane reflectors, shown in FIG. 5 as light-reflective elements 58. Theseelements are preferably integral with hub unit 80, comprising facetsformed contiguously with one another. Sharp edges are maintained atintersections 86 of adjacent facets and the facets form angle 84 (FIG.6) with axis 82, desirably forty-five degrees held to plus/minus tenminutes of arc. As shown in FIG. 7, hub unit 80 includes holes 80a and80b extending partially therethrough for receipt of fasteners 76 and 78(FIG. 4).

Support ring 62 defines circumferentially spaced lands 88 (FIG. 4) whichare inclined with respect to axis 82 at such angle as to provide foraxial alignment and the focusing of energy received by sphericalreflector elements 60 onto cigarette C. Reflective elements 60 arepreferably secured to lands 88 by a suitable cement 90, such as Eastman910 cement. Dowels 92 are tapped into front plate 66 immediatelyadjacent each reflective element 60 to further secure the elements infocusing position. Reflective elements 58 and 60 are employed incounterpart pairs, i.e., each reflective element 58 communicates with asingle one of reflective elements 60, the two communicating reflectiveelements comprising a successive pair of reflectors in a single lightpath extending to a distinct one of the peripheral locations oncigarette C to be perforated. Plane elements 58 serve to separateincoming light energy into separate parts, each part being focused byits counterpart spherical reflective element 60. While reflectiveelements 60 are mutually contiguous, reflective elements 58 are disposedin angularly successive spaced disposition about axis 82. In theillustrated example, fifteen facets of hub unit 80 are employed withfifteen spherical reflective elements, the latter elements being spacedfrom one another by twenty-four degrees of arc. Fifteen perforations areaccordingly made about the periphery of cigarette C at like twenty-fourdegree peripheral spacing.

Referring to FIGS. 8 and 9, each spherical reflective element 60 ispreferably formed, as in the case of hub unit 80, from a solid body ofhigh purity OFHC (oxygen-free high thermal conductivity) copper. Element60 exhibits a frontal surface 60a having a common spherical radius overits entirety with its depth of solid body extending beyond the basepoint 60B of the spherical radius being of dimension controlled toeffect proper focusing of received light energy. The reflective surfacesof both of elements 58 and 60 preferably have a protective coatingapplied thereto. Shims 61 (FIG. 4) may be employed as needed formaximizing energy transfer to cigarette C, as by assisting focusing.

In rendering the apparatus thus far described more suitable for theindustrial environment of cigarette perforation, or in like perforationinvolving the effective conversion of paper to a particulate cloud,pressurized gas is introduced, during use of the perforating optics ofFIGS. 3 and 4, into air inlet port 94. An annular channel 96 betweenmanifold 68 and baffle 98 conducts pressurized air to interior ports 100in respective gas communication with a second annular channel 102 ofmanifold 68 which, in turn, issues pressurized air through channels 104formed in front plate 66, each channel being adjacent to one of thespherical reflective elements 60. Pressurized gas is thereby forciblyissued across the spherical reflective elements to effect cleaningthereof.

To provide for essentially uniform volume flow of pressurized air fromeach of interior ports 100, the size of the ports is increased withincreasing distance thereof from air inlet port 94.

Back plate 64 (FIG. 3) is a solid member except for window cutouts 106formed therein at locations in registry with the light paths extendingfrom reflective elements 60 to cigarette C. By this preferredconfiguration of back plate 64, a sufficient back pressure is applied bythe back plate member on introduced pressurized gas as to cause flowthereof also across the surfaces of reflective elements 58 with window74 then serving as an exhaust port for such pressurized gas.

Unit 80 is shown with bore 80c (FIG. 4), enlarged in diameter from bore64a formed in the portion of plate 64 immediately supporting unit 80. Bythis arrangement, a set up and alignment pin (not shown) may be steppedin diameter to fit bore 64a and to otherwise represent cigarette C andreside in perforation drum groove 18 (FIG. 2). Following set up andalignment, the pin is removed and a light energy absorber may beinserted in bore 64a to protect against issuance of the laser outputleftwardly of plate 64 in FIG. 4.

In the illustrated practice discussed above, the placement of allreflective elements 58 and all reflective elements 60 in respectivecommon orientations with respect to axis 82 provides for common locationaxially of the cigarette for all perforations, i.e., the fifteenperforations define a perforated circular band about the cigarette. Theinvention contemplates such changes in disposition of its opticalelements as to arrange for other band configurations as may be desired,e.g., closed or open helical bands, etc. Further, while the use of apulsed laser has been discussed, the invention contemplates suitableshuttering of a continuous laser synchronously with movement of articlesto perforation position. The laser beam may also be shaped as desired,by masking, internally of the resonant cavity or externally thereof,e.g., to be square or ring-shaped in cross-section. Modification of thepreferred optics may of course be made to achieve like definition ofseparate light conducting paths, with conveyance of essentially focusedenergy to the article to be perforated, for example, by an arrangementof plural light sources and associated focusing elements in lieu of thepreferred single light source described herein.

In the illustrated arrangement, reflector elements 58 are plane and 60are spherical or aspherical. The elements may conversely be successivelyspherical (aspherical) and plane in the direction of light energypropagation. In another usable arrangement plane elements may besubstituted for reflectors 60 in the illustrated embodiment with afocusing lens in each distinct path, either between successivereflectors or between each output reflector and the cigarette. While theexemplary article has been characterized as cylindrical and peripherallyperforated while in single angular disposition about its longitudinalaxis, the invention is manifestly useful for such peripheral perforationof articles of other than cylindrical shape. These and other changes andvariations may evidently be introduced without departing from theinvention. The foregoing detailed description accordingly is intended asbeing illustrative and not limiting of the invention, the true spiritand scope thereof being set forth in the appended claims.

What is claimed is:
 1. In a method for making filter cigarettes whereintobacco rods are formed and wrapped and then joined to filter plugsbearing filter tipping wrap, and circumferentially spaced perforationsare made simultaneously in said filter tipping wrap of each cigarette byexposure of the outer surface of said filter tipping wrap to lightenergy, the improvement wherein such exposure step is practiced bygenerating a pulse of light and conducting separate spatial partsthereof simultaneously to locations circumferentially spaced on saidouter surface.
 2. The method claimed in claim 1 wherein saidcircumferentially spaced perforations are made while each said cigaretteis in preselected angular disposition with respect to the longitudinalaxis thereof.
 3. The method claimed in claim 1 wherein said perforationsare made at a common location axially of said plugs.
 4. A method inaccordance with claim 1 wherein:said separate parts of said beam are ofsubstantially equal intensity.
 5. The method claimed in claim 1 whereinlight-reflective surfaces are employed in such light energy conductingstep and including the further step of issuing pressurized gas onto saidlight-reflective surfaces.
 6. The method claimed in claim 1 wherein saidlight energy is laser-generated light energy.
 7. The method claimed inclaim 6 wherein said light energy is transverse excited atmosphericlaser-generated light energy.
 8. The method claimed in claim 1 whereinthe size of said perforations is controlled in part by preselecting theintensity of said light energy.
 9. The method claimed in claim 2 whereinthe size of said perforations is controlled in part by preselecting saidangular disposition to provide a predetermined size for each saidperforation.
 10. The method claimed in claim 9 wherein the size of saidperforations is controlled in further part by preselecting the intensityof said light energy.